If you haven’t been paying close attention, you might not have noticed a small but significant change in how Linux systems work with respect to runtime data. A re-arrangement of how and where it’s accessible in the file system started taking hold about eight years ago. And while this change might not have been big enough of a splash to wet your socks, it provides some additional consistency in the Linux file system and is worthy of some exploration.
To get started, cd your way over to /run. If you use df to check it out, you’ll see something like this:
$ df -k . Filesystem 1K-blocks Used Available Use% Mounted on tmpfs 609984 2604 607380 1% /run
Identified as a “tmpfs” (temporary file system), we know that the files and directories in /run are not stored on disk but only in volatile memory. They represent data kept in memory (or disk-based swap) that takes on the appearance of a mounted file system to allow it to be more accessible and easier to manage.